<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>grid方式</title>
  <style>
    .outer {
      display: grid;
      width: 100%;
      /* 设置行高 */
      grid-template-rows: 300px;
      /* 设置列宽 */
      grid-template-columns: 300px auto 300px;
    }
    .inner {
      background-color: lightgreen;
    }
    .mid {
      background-color: lightpink;
    }
  </style>
</head>
<body>
  <div class="outer">
    <div class="inner left">left</div>
    <div class="inner mid">mid</div>
    <div class="inner right">right</div>
  </div>
</body>
</html>